Geomorfni indikatorji tektonske aktivnosti na prehodu iz Posavskih gub v Ljubljansko kotlino v Tunjiškem gričevju

Tunjice Hills are located on the northwestern edge of Sava folds and represent a syncline structure with a fold axis in W - E direction. The Hills are composed of Miocene rocks. In thesis I investigate whether Quaternary tectonic activity occurs in the area, and whether active deformation can be attributed to the active folding of the Sava folds. I applied tectonic geomorphic methods to streams that flow over Tunjice Hills. I determined differences in sinuosity along the channel and investigated shapes of hypsometric curves and longitudinal stream profiles. I calculated values of hypsometric integrals and concavity parameters of maximal concavity and concavity factor and examined how far maximal concavity point is located from the source of the stream. The results show an increase in sinuosity when the rivers cross faults, at lithological changes, and in vicinity of confluence points. Most actively changed segments of streams are located in the westernmost stream and in central area of Tunjice Hills. Hypsometric curves for streams in the central part of Tunjice Hills have sigmoidal shape with possible tectonic activity in the lower part of the streams. From shape of hypsometric curve and values of hypsometric integral and concavity parameters, tectonic activity is apparent on the fault that runs along the Kamnik stream valley. Hypsometric curves, longitudinal stream profiles and concavity analysis showed that the eastern margin of the Hills is stable and in mature to old erosional stage which was also determined for a stream between westernmost Kamnik stream and central area. Tectonic activity is present on faults that belong to Sava fault zone. There is no indication of active deformation in Sava folds trend.Tunjiško gričevje se nahaja na severozahodnem robu Posavskih gub in predstavlja sinklinalno strukturo z osjo gube v smeri W - E. Gričevje sestavljajo miocenske kamnine. Namen naloge je določitev prisotnosti tektonske aktivnosti na območju Tunjiškega gričevja ter če so prisotne deformacije, ki potrjujejo enako aktivno gubanje kot v Posavskih gubah. V nalogi sem uporabila tektonsko geomorfološke metode na potokih, ki tečejo po območju Tunjiškega gričevja. Določevala sem spremembe v vijugavosti potokov, evidentirala obliko hipsometričnih krivulj in vzdolžnih profilov in izračunala vrednosti hipsometričnih integralov in parametrov konkavnosti, kot so maksimalna konkavnost in njena oddaljenost od izvira potoka ter konkavnostni faktor. Rezultati kažejo, da se vijugavost potokov poviša na območjih prelomov, sprememb v litologiji in v okolici sotočij. Največje spremembe v vijugavosti se nahajajo na najbolj zahodnem in osrednjem delu Tunjiškega gričevja. Hipsometrične krivulje potokov v osrednjem delu gričevja imajo sigmoidalno obliko in nakazujejo prisotnost tektonske aktivnosti v spodnjem delu potokov. Oblika hipsometrične krivulje, vrednosti hipsometričnega integrala in konkavnostnih parametrov kaže na aktivnost preloma v dolini potoka Kamnik. Hipsometrične krivulje, vzdolžni profili in analiza konkavnosti so pokazali da je vzhodni del gričevja v stabilnem stanju in v starejših erozijskih fazah, kar je značilno tudi za potok med najbolj zahodnim potokom Kamnik in osrednjem območjem. Tektonska aktivnost je vezana na prelome v coni Savskega preloma. Deformacij v smeri aktivnega gubanja Posavskih gub ni bilo zaznati

Evaluating mineral matter dynamics within the peatland as reflected in water composition

Peatland hydrology plays an important role in preserving or changing the record in any consideration of past atmospheric deposition records in peat bogs. The Šijec bog, located on the Pokljuka plateau in Slovenia, is one of the largest ombrotrophic peatlands. We sampled the surface pools, pore water, drainage from the peatland, and karst streams not connected to the peatland. Additionally, we sampled the precipitation, as ombrotrophic peatlands receive mineral matter solely from the atmosphere. The results of the evaluation of the chemical and isotopic composition indicated different origins of dissolved mineral matter in different water types. The components originating from the bedrock and surrounding soils (Ca, Mg, Al, Si, Sr) predominated in the streams. The chemical composition of the peatland drainage water revealed the significant removal of major components from the peatland, particularly elements like Al, Fe, and REE, and metals that are readily dissolved in an acidic environment or mobile in their reduced state. Despite their solubility, concentrations of metals (As, Cr, Cu, Fe, Ni, Pb, Ti) and REE in surface pools remained higher than in the drainage due to incomplete elimination from the peatland. The composition of pore water reflects variations among the W and E parts of the peatland, indicating a heterogenous hydrological structure with different dynamics, such as an additional source of water at approximately 90 cm depth in the NW part. The chemical composition and isotope signature (18O and 2H) of pore water additionally indicated a heterogeneous recharge with residence times of less than a year. The overall analysis indicated a predominantly ombrotrophic type and a small part in the NW area of the peatland as a minerotrophic type of peat

Evaluation of ombrotrophic peatland environment as tracer of past atmospheric deposition

We studied Šijec bog on Pokljuka plateau. Using geophysical methods (GPR, ERT), we determined the subsurface morphology of the peatland and created a formation model, which indicates different development stages of the peatland. Peatland is composed of four depressions which vary in depth, surface topography, and water saturation at the surface. Atmospheric mineral matter input to the peatland is mainly composed of silicates, carbonates, organic particles and Fe-oxyhydroxides. Mineral matter deposited on the acidic, organic matter-rich peatlands surface can be partially or totally dissolved. Dissolved and solid mineral matter can be retained through plant uptake, physical entrainment, or complexation by organic matter. Chemical composition of peatland outflow water reveals significant removal of elements like Al, Fe, and REE which are soluble in acidic environment or mobile in their reduced state. Metals (e.g. As, Cr, Cu, Ni, Pb) remain in surface pool waters and upper layers of peat due to lower solubility in peatland environment and binding to organic matter. Geochemical analysis of peat confirmed differences between development stages, which were further emphasised with water geochemical composition indicating additional water and mineral matter sources in NW area of the peatland. Comparison of C/N ratios and trace element distributions along peat profile reveals elevated content of elements like As, Hg, and Pb in upper peat layers due to anthropogenic influence and peat decomposition, and its related loss of organic matter. Peat cores show large variabilities in element content among sampling locations, showing the importance of holistic approach to research of peatland environment.Raziskovali smo barje Šijec na Pokljuki. Z geofizikalnimi metodami (georadar, ERT) smo določili podpovršinsko morfologijo barja ter izdelali model nastanka, ki kaže različne razvojne stopnje barja. Barje sestavljajo štiri kotanje, ki se razlikujejo po globini, topografiji površja in prisotnosti vode na površju. Silikati, karbonati, organski delci in Fe-oksihidroksidi prevladujejo v mineralni snovi odloženi iz atmosfere. Mineralna snov se po odložitvi na kislo in z organsko snovjo bogato površje barja delno ali popolnoma raztopi. Raztopljena in trdna mineralna snov se lahko zadrži v barju z vnosom v rastline, ujetjem ali tvorjenjem kompleksnih spojin z organsko snovjo. Kemična sestava vod, ki tečejo iz barja kaže na izločanje elementov, ki so topni v kislem okolju ali mobilne v redukcijskem stanju, kot so npr. elementi Al, Fe in REE. Kovine (npr. As, Cr, Cu, Ni, Pb) se deloma zadržijo v vodah površinskih bazenov in zgornjih plasteh šote zaradi nekoliko slabše topnosti v barjanskem okolju ter vezave na organsko snov. Z geokemično opredelitvijo šote smo potrdili razlike med razvojnimi stopnjami, ki so dodatno potrjene s kemično sestavo vode, ki kaže na dodatne vire vode in mineralne snovi v SZ delu barja. Primerjava C/N razmerij in porazdelitev elementov po profilu šote kaže na povišane vsebnosti elementov kot so As, Hg in Pb v zgornjih plasteh šote zaradi antropogenega vpliva in razgradnje šote ter s tem posledično izgube organske snovi. Jedra šote kažejo velike razlike v vsebnostih elementov med lokacijami vzorčenja, kar kaže na potrebo po celovitem razumevanju barjanskega okolja

Characterization of atmospheric deposition as the only mineral matter input to ombrotrophic bog

Ombrotrophic peatlands contain a very small percentage of mineral matter that they receive exclusively from atmospheric deposition. Mineral matter deposited on the Šijec bog was characterized using scanning electron microscopy coupled with energy dispersive spectroscopy (SEM/EDS). We collected solid atmospheric deposition from snow, rainwater, and using passive samplers. Samples were collected at average atmospheric conditions and after two dust events. Size, morphology, and chemical composition of individual particles were determined. We distinguished four main particle groups: silicates, carbonates, organic particles, and Fe-oxyhydroxides. Silicate particles are further divided into quartz and aluminosilicates. Proportions of these groups vary between samples and between sample types. In all samples, silicate particles predominate. Samples affected by dust events are richer in solid particles. This is well observed in passive deposition samples. Carbonates and organic particles represent smaller fractions and are probably of local origin. Iron-oxyhydroxides make up a smaller, but significant part of particles and are, according to their shape and chemical composition, of both geogenic and anthropogenic origin. Estimated quantity and percentage of main groups vary throughout the year and are highly dependent on weather conditions. Dust events represent periods of increased deposition and contribute significantly to mineral matter input to peatlands

Investigating peatland stratigraphy and development of the Šijec bog (Slovenia) using near-surface geophysical methods

Owing to their anoxic environment, peatlands play an important role in the preservation of records documenting past atmospheric depositions. To determine past records, data on peat stratigraphy and bog development are needed. Ground penetrating radar (GPR) was used to determine the peat thickness and morphology of the Šijec bog on the Pokljuka plateau in Slovenia, which will serve as a basis for further geochemical studies. Information on the stratigraphy below the peat/clay boundary was acquired by applying electrical resistivity tomography (ERT). The GPR results reveal four depressions within the peat bog, which are separated by elevated ridges. Within the depressions the peat reaches a depth of 6–9 m. The edges of the bog are flat, with peat thickness ranging from 2 to 4 m. The reach of the GPR was complemented with manual peat probing. A comparison of the depths obtained using GPR and the peat probe reveals that the results of both methods correspond well in most locations. The ERT indicated similar peat depthspeat responds with high electrical resistivity. In contrast, clayey sediments with low resistivity are found below the peat. The peat depressions are underlain with larger clayey depressions reaching more than 20 m in thickness and represent lake sediments. The complementary geophysical methods proved to be an efficient approach with which we can delineate the peat morphology and the underlying stratigraphy. Both indicate bog formation from a lake with four deeper depressions, that are separated by glacial deposits. The results presented here show the potential for geophysical methods to infer formational processes in peatlands, showing the presence of a series of isolated basins that later coalesced into a single peat landform. This interpretation is consistent with previous conceptual models from studies in boreal regions

Geochemical background and threshold for 47 chemical elements in Slovenian topsoil

Geochemical background and threshold values need to be established to identify areas with unusually high concentrations of elements. High concentrations are caused by natural or anthropogenic processes. The <2 mm fraction of 817 collected topsoil (0 – 10 cm) samples at a 5 × 5 km grid on the territory of Slovenia was analysed. Results are used here to establish the geochemical background variation and threshold values, derived statistically from the data set, in order to identify unusually high element concentrations for these elements in the soil samples. Geochemical threshold values were determined following different methods of calculation for (1) whole of Slovenia and (2) for 8 spatial units determined on the base of geological structure, lithology, relief, climate and vegetation. Medians and geochemical thresholds for whole of Slovenia were compared with data for Europe and for southern Europe separately, since large differences in the spatial distribution of many elements are observed between northern and southern Europe. Potentially toxic elements (PTEs), namely As, Cd, Co, Cr, Cu, Hg, Mo, Ni, Pb, Sb, and Zn, are of particular interest. Medians of these PTE elements are all higher in Slovenia than in southern Europe. Medians of Pb and Mo are 1.5 times higher and medians of Hg and Cd are even more than 2 times higher in Slovenia. Geochemical thresholds for As, Cr, Co, Ni, Sb and Zn are of similar values in both Slovenia and southern Europe and some lower for Cu and Ni. Up to 1.5 times higher are tresholds in Slovenia for Mo and Pb and more than 2.5 times higher for Cd and Hg. These values were then compared to existing Slovenian soil guideline values for these elements